In the Marvel Universe there is a real Santa Claus who is an ancient and very powerful mutant. He possesses powers that come from both his mutant dna and from a variety of magical sources. His exact powers and origins are not entirely clear but he is very old and very powerful. He also does live at the North Pole, with elves, and gives presents to all of Earth's children on Christmas.

Fun facts:
Santa has faced a variety of foes in Marvel comics and has proven very resilient despite avoiding violence.

He once turns the evil Brotherhood of Mutants into Toys

Cerbro once located him as the most powerful Mutant on the planet!

Doctor Octopus once took over the North Pole but he was stopped by Antman and Santa Claus

Once Santa was injured while flying over Latveria the kingdom of Dr Doom. Dr Doom showed a surprising amount of Christmas spirit. Doom used his Doom bots to finish the Christmas deliveries.